A train covers 360 km at a uniform speed. If its speed had been 5 km/h more, the journey would have taken 1 hour less. The original speed is:

Question

Accepted Answer

40 km/h. With speed x, 360/x − 360/(x + 5) = 1, so 360 × 5 = x(x + 5), i.e. x² + 5x − 1800 = 0. Then x = (−5 + √(25 + 7200))/2 = (−5 + 85)/2 = 40. Check: 360/40 = 9 h and 360/45 = 8 h.

A train covers 360 km at a uniform speed. If its speed had been 5 km/h more, the journey would have taken 1 hour less. The original speed is:

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